Mungan A Gorkem, Erol Bulent, Akduman Bulent, Bozdogan Gurdal, Kiran Sibel, Yesilli Cetin, Mungan N Aydin
Department of Biochemistry, Zonguldak Karaelmas University, School of Medicine, Kozlu Zonguldak, Turkey.
Clin Chem Lab Med. 2007;45(7):912-6. doi: 10.1515/CCLM.2007.501.
The aim of this study was to evaluate age-related changes in free/total prostate-specific antigen (f/t PSA) ratio, focusing on the avoidance of unnecessary prostate biopsies.
A total of 898 men aged 30-88 years without a history of prostate surgery and disease were enrolled into the study. Serum tPSA, fPSA and f/t PSA ratios were determined for the study population and for different age categories. All males who had suspicious digital rectal examination and tPSA >4 ng/mL underwent transrectal ultrasonography-guided prostate biopsy. Receiver operating characteristic (ROC) curves for each group were generated by plotting the sensitivity vs. 1-specificity for the f/t PSA ratio. The sensitivity and specificity were obtained using different f/t PSA ratio cutoffs for different age groups.
Prostate cancer was detected in 63 patients (7%). Age-specific cutoffs were determined according to likelihood ratios at the levels of 10%, 15% and 15% f/t PSA ratio for ages 50-59, 60-69 and >/=70 years, respectively. However, a single cutoff of 10% is recommended across all age ranges (positive likelihood ratio 2.36). ROC curves demonstrated that the area under the curve (AUC) was significant for all patients with initial PSA of 4-10 ng/mL (AUC 0.703-0.796), except for the >/=70-year age group (AUC 0.549).
The current study showed that the use of f/t PSA ratio in patients with PSA levels of 4-10 ng/mL should enhance the specificity of PSA screening and decrease the number of unnecessary biopsies. f/t PSA levels may show dissimilarities according to age and ethnicity, so further studies are warranted to identify this relationship.
本研究旨在评估游离/总前列腺特异性抗原（f/t PSA）比值与年龄相关的变化，重点是避免不必要的前列腺活检。
共有898名年龄在30 - 88岁、无前列腺手术和疾病史的男性纳入本研究。测定了研究人群及不同年龄组的血清总PSA（tPSA）、游离PSA（fPSA）和f/t PSA比值。所有直肠指检可疑且tPSA>4 ng/mL的男性均接受经直肠超声引导下的前列腺活检。通过绘制f/t PSA比值的敏感性与1-特异性的关系图，生成每组的受试者操作特征（ROC）曲线。使用不同年龄组的不同f/t PSA比值临界值获得敏感性和特异性。
63例患者（7%）检测出前列腺癌。根据似然比分别确定了年龄特异性临界值，50 - 59岁、60 - 69岁和≥70岁的f/t PSA比值水平分别为10%、15%和15%。然而，建议所有年龄范围采用单一的10%临界值（阳性似然比2.36）。ROC曲线显示，初始PSA为4 - 10 ng/mL的所有患者曲线下面积（AUC）具有显著性（AUC 0.703 - 0.796），≥70岁年龄组除外（AUC 0.549）。
本研究表明，在PSA水平为4 - 10 ng/mL的患者中使用f/t PSA比值应可提高PSA筛查的特异性，并减少不必要活检的数量。f/t PSA水平可能因年龄和种族而异，因此有必要进一步研究以确定这种关系。
